Fix imports.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=150732864

library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/mp4/AtomParsersTest.java

@@ -17,7 +17,6 @@ package com.google.android.exoplayer2.extractor.mp4;
 
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
-
 import junit.framework.TestCase;
 
 /**

library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac3Extractor.java

@@ -26,7 +26,6 @@ import com.google.android.exoplayer2.extractor.SeekMap;
 import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
-
 import java.io.IOException;
 
 /**

library/core/src/main/java/com/google/android/exoplayer2/metadata/emsg/EventMessage.java

@@ -17,7 +17,6 @@ package com.google.android.exoplayer2.metadata.emsg;
 
 import android.os.Parcel;
 import android.os.Parcelable;
-
 import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.util.Util;
 import java.util.Arrays;

library/core/src/main/java/com/google/android/exoplayer2/source/chunk/BaseMediaChunk.java

@@ -16,7 +16,6 @@
 package com.google.android.exoplayer2.source.chunk;
 
 import com.google.android.exoplayer2.Format;
-import com.google.android.exoplayer2.extractor.DefaultTrackOutput;
 import com.google.android.exoplayer2.upstream.DataSource;
 import com.google.android.exoplayer2.upstream.DataSpec;
 

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsMasterPlaylist.java

@@ -17,7 +17,6 @@ package com.google.android.exoplayer2.source.hls.playlist;
 
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.util.MimeTypes;
-
 import java.util.Collections;
 import java.util.List;
 

library/ui/src/main/java/com/google/android/exoplayer2/ui/AspectRatioFrameLayout.java

@@ -20,7 +20,6 @@ import android.content.res.TypedArray;
 import android.support.annotation.IntDef;
 import android.util.AttributeSet;
 import android.widget.FrameLayout;
-
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;